Figuring out where Woody Allen's career began its downward spiral requires little more than a glance at his filmography: 1992, with Shadows and Fog. It may be coincidental that his ugly breakup with Mia Farrow occurred shortly thereafter, but Allen hasn't made a truly great or memorable motion picture since the early 1990s. Lately, Allen's films have sunk into a state of heightened mediocrity - sporadically entertaining, but often disappointing, at least for those clinging to the hope that Allen will return to "form." I no longer expect great things from a Woody Allen movie, so something like Melinda and Melinda doesn't leave me despondent. This is the Allen we have come to recognize over the past decade.

To be fair, Melinda and Melinda has a fascinating premise; it's the execution that's sloppy. The film examines how a single set of circumstances can be used as the basis for both a comedy and a tragedy. We are presented with two stories to illustrate this. Both feature a young woman named Melinda (Radha Mitchell) crashing a dinner party. From there, the tales diverge, although there are points of commonality sprinkled throughout. To keep the time lines straight, Allen presents them in parallel, switching back and forth at will (with only Radha Mitchell's hairstyle to keep us from confusing the two versions of Melinda), rather than telling one story to its conclusion, then offering the second.

In the "tragedy," Melinda is a sad, lonely woman who, having lost custody of her children to her ex-husband, has ended up in New York City at the apartment of a high school girlfriend, Laurel (Chloe Sevigny). Laurel welcomes her, but Melinda's presence deepens the strain on Laurel's marriage to aspiring actor Lee (Jonny Lee Miller). Lee is chronically unfaithful, and Laurel is catching on. And, just as Melinda appears to be getting her life together and has found a new man to date (Chiwetel Ejofor), a new setback sends her life spiraling out of control.

Meanwhile, in the "comedy," Melinda is the downstairs neighbor of an ambitious film director, Susan (Amanda Peet), and her nebbish husband, Hobie (Will Ferrell). Hobie and Susan do not have a good marriage, and Hobie finds himself attracted to Melinda. But, by the time the circumstances are right for him to act on his feelings, she is involved in a relationship with someone else (all the while being secretly in love with Hobie).

One of the peculiar things about Melinda and Melinda is how Allen regards the terms "tragedy" and "comedy." The two stories aren't that different in tone - one is a little lighter than the other, but there isn't a great divide between them. The "comedy" has more of Allen's traditional shtick (as brought to the screen by Farrell), but it's not all that funny. And the "tragedy" plays more like a second-rate melodrama. There is an imbalance in interest, which is a problem. The "comedy" is more engaging than the "tragedy." Half-way through the film, I found myself wishing that Allen would dispose of moping Melinda and deal with the frothier version of the character.

As the obvious Allen stand-in, Farrell does an adequate job of channeling the writer/director, and doesn't go as overboard as Kenneth Branagh did in Celebrity. However, forcing Farrell into this role negates his comedic strengths, and he comes across as a bigger, younger version of Allen. Plus, all of the self-deprecating, angst-riddled lines that Allen writes for himself (or his stand-in) have gotten a little old over the years. He's repeating himself, and it shows.

The film's bright spot is Radha Mitchell, a fine actress who has spent much of her career below the horizon of public notice (her biggest role to date was probably in Pitch Black). Here, she gets a chance to live every actor's dream - take a single character and develop her in two radically different directions. Mitchell is more luminous in the "comedy," but that's not a surprise, since her character isn't caught up in haze of booze, pills, and self-pity. If there's a reason to see Melinda and Melinda, it's for Mitchell.

One could argue that Melinda and Melinda is Allen's most ambitious film in years. Had he pulled it off, this might have been the movie fans have been hoping for. Unfortunately, the script is weakly constructed. Dialogue occasionally feels stilted and too obviously written, Allen's comedic touches are not sharp, and only the characters in the "comedy" generate any audience sympathy. Provided you don't actively dislike Allen, you'll find Melinda and Melinda diverting, but not worth the extra effort that may be necessary to locate a theater playing it. (Fox Searchlight, suspicious of the film's reception, is limiting distribution.)